As for "Love Gonna Pack Up (and Walk Out)" -- the song was recorded in 1972 and reached the top of the charts ... and Poindexter says neither Cash Money nor Bow Wow ever obtained permission to sample it.

Poindexter claims he reached out to Cash Money for an answer, and was redirected to Bow Wow's attorneys, who then directed him back to Cash Money ... which is why Cash Money's currently in his crosshairs.

Poindexter wants $600,000 in punitive damages, plus interest. Cash Money has yet to respond to the suit. We reached out to the label for comment -- so far, no word back.

It's not the first time Poindexter's sued rappers over his music -- the producer has already filed suit against 50 Cent and Kanye West over similar song-stealing allegations.